It has been well known that when a silver halide light-sensitive photographic material is exposed imagewise and developed, an oxidation product of aromatic primary amine color developing agent reacts with a coupler to form dyes such as indophenol, indoaniline, indamine, azomethine, phenoxyazine, phenazine and their analogues, thus color images are formed. Usually, in such photographic system, a color reproduction technique based on the subtractive process is used; wherein the light-sensitive silver halide color photographic material used comprises the blue-sensitive, green-sensitive, and red-sensitive silver halide emulsion layers correspondingly containing yellow dye forming, magenta dye forming, and cyan dye forming couplers, i.e. couplers whose sensitivities complementary to the color sensitivities of these emulsion layers.
The couplers useful for forming the yellow dye image include acylacetanilide couplers; and the couplers useful for forming the magenta dye image include pyrazolone, pyrazolobenzimidazole, pyrazolotriazole, and indazolone couplers; while the examples of the commonly used cyan dye image forming couplers include phenol and naphthol couplers.
The so-obtained image is required to be stable even when exposed to light for a long time, or even when stored under a high temperature or high humidity. Moreover, a silver halide color photographic light-sensitive material (hereinafter referred to as color photographic material) which does not cause yellow stain (hereinafter referred to as Y-stain), by heat or moisture, in the non-colored portion has been a long-felt demand in the art.
As compared with yellow dye forming couplers (hereinafter referred to as yellow coupler)and cyan dye forming couplers (hereinafter referred to as cyan coupler), magenta dye forming couplers (hereinafter referred to as magenta coupler) are liable to cause more significant Y-stain by light, moisture, or heat in the non-colored portion, as well as fading in the colored portion caused by light, and this disadvantage often incurs a problem.
The couplers commonly used for forming magenta dye image are 5-pyrazolones. The magenta dyes formed from the 5-pyrazolone magenta couplers have a big problem in having secondary spectral absorption in the vicinity of 430 nm, in addition to the primary spectral absorption in the vicinity of 550 nm. Therefore, various studies have been conducted to solve this problem.
The magenta coupler having an anilino group on the 3 position of 5-pyrazolone, which exhibits less significant secondary absorption, is known to be useful in obtaining color images for print. The related techniques are disclosed, for example, in U.S. Pat. No. 2,343,703 and British Patent No. 1,059,994.
However, these magenta couplers are disadvantageous as they are significantly inferior in the image preservability, especially, in the stability of dye images to light, as well as in larger magnitude of Y-stain in the non-colored portion.
Other means proposed for limiting the above-mentioned secondary absorption of magenta couplers in the vicinity of 430 nm are magenta couplers such as pyrazolobenzimidazole couplers in British Patent No. 1,047,612; indazolone couplers in U.S. Patent No. 3,770,447; 1H-pyrazolo[5,1-c]-1,2,4-triazole couplers in U.S. Pat. No. 3,725,067, British Patent Nos. 1,252,418, and 1,334,515; 1H-pyrazolo[1,5-b]-1,2,4-triazole couplers in Research Disclosure 24531 (1984); 1H-pyrazolo[1,5-c]-1,2,3-triazole couplers in Research Disclosure 24626 (1984); 1H-imidazo[1,2-b]pyrazole couplers in Japanese Patent Publication Open to Public Inspection (hereinafter referred to as Japanese Patent O.P.I. Publication) No. 162548/1984 and Research Disclosure 24531 (aforementioned); 1H-pyrazolo[1,5-b]pyrazole couplers in Research Disclosure 24230 (1984); and 1H-pyrazolo[1,5-d]tetrazole couplers in Research Disclosure 24220 (1984). Among them, the dyes formed from 1H-pyrazolo[5,1-c]-1,2,4-triazole couplers,1H-pyrazolo[1,5-b]-1,2,4-triazole couplers, 1H-pyrazolo[1,5-c]-1,2,3-triazole couplers, 1H-imidazo[1,2-b]pyrazole couplers, 1H-pyrazolo[1,5-b]pyrazole couplers and 1H-pyrazolo[1,5-d]tetrazole couplers are advantageous in terms of color reproduction, as compared with the previously mentioned dyes formed from 5-pyrazolones having an anilino group on the 3 position; in having significantly smaller secondary absorption in the vicinity of 430 nm, and in causing relatively small Y-stain due to light, heat, or moisture, in the non-colored portion.
However, the azomethine dyes formed from these couplers are disadvantageous for their substantially lower light-fastness `nd liability to discloration, and by this disadvantage, the property of color photographic material, especially that of color photographic material for print is substantially deteriorated.
Incidentally, methods in Japanese Patent O.P.I. Publication Nos. 125732/1984 and 262159/1985 propose, as a means to improve the light-fastness of the magenta dye image formed from pyrazoloazole magenta couplers, to incorporate phenol-type or phenylether-type compounds into pyrazoloazole magenta couplers.
These methods, however, are still insufficient in preventing the magenta dye image fading by light, in addition to the inability to prevent discoloration by light.